Vibratory spiral conveyors are generally known in the art. Such apparatus typically includes a spiral deck, formed in the shape of a helix, and a source of vibration operatively coupled to the deck. The spiral conveyor may be a brute force system, such as that disclosed in U.S. Pat. No. 2,927,683 to Carrier, or a two-mass system, as disclosed in U.S. Pat. No. 5,024,320 to Musschoot.
Spiral conveyors are often used to heat or cool work pieces or granular material. With foundry castings, for example, red hot castings (which may have a temperature of approximately 1000 degrees F. or more) are fed into the spiral conveyor. Cool air is directed over the castings as the castings travel up the spiral, thereby to reduce the temperature of the castings. Conventional spiral conveyors direct air from a center axis of the conveyor outwardly, with or without nozzles for directing the air toward the castings. The air is exhausted out an exterior of the spiral conveyor.
In one conventional design, air is generally directed radially across the spiral conveyor from the center core inlets to the outer periphery outlets. As a result, the inner facing side of the castings (or the inner row, should more than one row of castings be fed into the conveyor) will receive a lower temperature air than the outer facing side (or outer row).
In another conventional design, both the air inlet and air outlet are positioned at the outer periphery of the spiral conveyor. As the air enters the spiral conveyor area, it passes about the center core in at least two separate sub-streams. The air then exhausts from the spiral conveyor through a common outlet.
The castings can include foundry sand that may become entrained in the cooling air stream. Typically very light particles, such as small grains of sand or sprue, are picked up by the air stream. Consequently, a filter house is typically connected to the outlet air stream to collect the particles before the air is exhausted to atmosphere. The filter house is typically provided as a separate unit, and is located outside of the spiral conveyor, thereby requiring additional space for the conveying equipment.